[Therion] Displays in the landscape

[Graham Mullan]

Amongst other things, Julian Todd wrote: 

"The big idea is that we should be able to walk around the landscape holding
our big tablet in front of us giving an X-ray view of the cave underneath
us.  Maybe you could hold it up against the mountain and see all the cave
systems inside of it."

An excellent idea, but it does remind me of something I sometimes have a
problem with in Aven and Loch. If you are viewing a large area model with
lots of passage over a wide area, then the picture can get very 'noisy' as
you move around. It may be worth giving an option to fade out all the
passage more than a given distance away from the view point so that you can
concentrate on the stuff nearest to you without getting your view obscured
by stuff that is actually some distance away.

Graham